Fuel supply pump for diesel engine fuel injection equipment



FUEL. SUPPLY PUMP FOR DIESEL ENGINE FUEL. INJECTION EQUIPMENT Filed March 18, 1954 May 14, 1957 R. w. BOEHRINGER 2 Sheets-Sheet l INVENTOR. fioezer W. Fume/Mam Ufl s r UEL- sUm LY :PUMP FOR DIESEL ENGINE FUEL INJECTION EQUIPMENT Robert W. Boehringer, Whitestone, N. Y. Application March 18, 1954, Serial No. 417,076

3 Claims. (Cl. 103-4) This invention relates to fuel supply pumps whichsupply fuel oil to "fuel oil injection equipment of diesel engines andthe combination of such fuel supply pumps with the fuel injection equipment.

The generally used diesel engine fuel oil injection equipinent, comprises a suitably driven cant-shaft with cam lobes within a cam shaft housing which actuate in the proper timesequence a series of plungerpump barrels,

one for each engine cylinder, for delivering an accurately metered quantity of fuel oil from a fuel supply sump duct under high-pressure to the spray nozzles of the different engine cylinders and injecting the fuel in definite timing relation to the engine cycle and within the required injection period. In such known injection equipment a portionof thefuel oil that'is supplied to the cam actuated plunger barrel leaks from the sump duct into the cam shaft housing compartment and accumulates therein at such'high' level that it enters the cam shaft bearings and leaks therethrough to the exterior of the housing. 'For many years past,-the accumulation of leakage fuel oil in the cam shaft compartment of such fuel injection-equipment has been the-cause of great ditficulties andtroublesfor which no satisfactory solution was found heretofore.

An object of theinvention is -the elimination of excessive accumulation of leaking fuel oil inthe cam shaft housing compartment of such known fuel injection equipment without adding thereto any further-moving mechanical elements.

According to the invention, a partof the oil-fuel-supply pump'-which is'provided'for pumping the fuel oil from a fuel tank to the sump duct-is utilized as a pump for pumping from the cam shaft housing-the fuel oil which leaks into it .andthereby assure that leaking fuel oil does not accumulatein the cam shaft compartment above a predetermined level at which it becomes a source of trouble.

The foregoingand other-objects -ofthe invention will be best understood from the following description of exemplifications' thereof, reference being hadto the accompanying drawings wherein;

Fig. lis a diagrammatic view of a known type of fuel injection equipment, modified in accordance with the invention to eliminate accumulation of leakingfuel oil in the cam shaft housingthereof;

Fig. 2 is a cross-sectional view of a partof the fuel injection pump structure showing how it is combined atent -Fig. 7 is a cross-sectional view of the fuel pump along lines 77 of Fig.2.

The present invention was evolved in connection with the-difliculties encountered with the fuel injection equipment manufactured for use in injecting metered fuel under pressure into the cylinders ofa diesel engine and a practical embodiment of the invention will be described hereinafter in connection with such standard equipment.

Fig. l is a diagrammatic view of the general arrangement of standard fuel injection equipment. It comprises a fuel injectionpump'10 which is supplied with oil from fuel tank 31. and is arranged to deliver through a series of fuel lines -31--1, an accurately meter-ed quantity of fuel oil'under high pressure to a series of fuel injection nozzles 31-2 of several cylinders of the diesel engine, each fuel line 31-4 leading to .a-diiferent injection nozzle.312,

only one of which is shown. The fuel injection pump 10 shown is of a standard type, and Fig. 2 of the drawings is a cross sectional view of one of the injection pump units: 26. "The fuel injection pump it comprises a cam shaft 12 revolvable on two ball bearings 13 heldmounted in opposite endwalls 14 of the metal housing 15 of injection pump '10. The cam shaft 12 has a plurality of axially displaced cam lobes '15 arranged to actuate in proper time sequence a plurality of injection pump units 20 (Fig. 2) mounted side ,by side within the pump housing 15. Referring to Fig. ,2, each injection pump unit 20 comprises an elongatedpumpplunger barrel 21 forming part of a barrel assembly slidablypositioned within a guide way of the housing ISand having-its lower plunger end 23 associated with a helical return spring 24 which returns and biases'the plunger barrel assembly 21 to its downward position. The barrel assembly 21 is combined with a gear segment member 25 the gear teeth of which engage the teeth of an elongated gear rack 26 slidably movable within a housing guide way in a direction parallel to the cam shaft 12 for imparting a rotary control movement tothe plunger barrel 21 and its barrel helix 22 to thereby controllably change the amount of fuel injected into the engine cylinders; all-inthe known conventional'manner.

The cam shaft 12 has aseries of axially displaced cam lobes 16, one for :each injection plunger barrel 21, the respective camlobe .16 being positioned for rotation in a planeextending vertically through the axis of the plunger barrel 21 as seen in Fig. 2. The rotation of the cam lobe 16transmits a corresponding upward'longitudinal sliding motion to the plunger barrel assembly 21 by a means of a cylindrical plunger tappet 28. The plunger tappet 28 is slidable within a cylindrical guide way of a partition wall :151 of the housing 15 whichiseparates the cam shaft compartment 12-4 fromthe injection compartment 2*1--1 ofthehousing 15. The plungertappet28 carries revolvablyon a suitable'shaft a guide tappet roller 29 which .rjides .on the cam surface ofcam lobe 16 so that the rotation of the cam lobe s16 acting on the tappet roller29 transmits a corresponding longitudinal sliding motion to the plunger barrel 21. .A fueloil sump duct 17 within the housing has opening 18 through which the fuel oil enters into the injection spaces of the housing 15 so that'each upward movement. of the plunger barrel 21 delivers the desired .metered volume of fuel oil under the desired pressure to the associated injection line '51 in the known conventional way.

In order to supply fuel oil to the fuelsump duct 18 of thefuel injection units 2t) (Fig. 2), .the equipment (Fig. l) is provided with a fuel tank 31 containing a supply of;fuel oil, a fuel-feed line 32 leading from the .supply duct to a fuelsupply pump 4t} which pumps :the

fuel oil fromthetank 31 and delivers it through a delivery duct 34 to the inlet 35 .of thefuel sump duct 18. The excess oftfuel oil delivered by the supplypump 40-to the fuel sump duct 18 is discharged through an oil outlet 3 18-1 thereof into the fuel return line 33 which returns it to the fuel tank.

The fuel supply pump 40 is shown structurally in Figs. 3 and -7 and diagrammatically in Fig. 4. It comprises a metallic housing structure 41 which is secured to a lower side wall portion of the injection pump housing 15 (Fig. 2) in the region of the cam shaft 12, with a coupling portion 42 of the supply pump housing 41 being seated in a bore of the injection pump housing 15. Within a cylindrical pump space 43 of the pump housing 41 is slidably mounted a cylindrical pump barrel 44 to which a slidable pumping motion is imparted by a push rod 45 seated in a guide way of the pump housing 41. A biasing coil spring 46 acting on the inner end surface of the pump barrel 44 serves to return it to its outward end position in rightward direction as seen in Figs. 4-6 against the action of the push rod 45 which moves it to its inward position.

The push rod 45 extends from a cylindrical pump tappet 51 slidably movable within a cylindrical guide way 52 of the cylindrical coupling portion 42 of the pump housing 41 so that slidable movement imparted to the pump tappet 51 will impart a corresponding slidable movement through its push rod 45 to the supply pump barrel 44 for pumping fuel from the oil tank 31 to the sump duct 17 of the injection pump 20. The pump tappet 51 carries revolvably on a suitable shaft a tappet roller 54 which rides on a cam lobe 16 of the cam shaft so that each rotation of the cam shaft and its cam lobe 16 shall impart the proper longitudinal sliding motion to the pump tappet 51 and therethrough to the supply pump barrel 44. Referring to Figs. 4 and 6 the supply pump 40 operates as follows, the rotation of the cam shaft lobe 16 actuates the supply pump tappet 51 in inward direction to the left (as seen in Fig. 4) thereby moving through push rod 45 the supply pump barrel 44 in inward direction and expelling oil filling the pump space 43, the expelled oil being discharged through one-way valve 61 into the delivery duct 34 which delivers the oil to the sump duct inlet 35 of the injection pump 10. In the next part of the rotation of the cam lobe 16, the biasing spring 65 returns the released pump barrel 44 to its outward right position as seen in Fig. 4, thereby pumping fuel oil from the fuel tank 31 through fuel supply duct 32 and one-way valve 62, which then prevents the return --of oil from the pump cylinder space 43 into the fuel supply duct 32.

Since the fuel injection equipment including the supply pump thus far described in connection with Figs. 1-7 is of the standard construction a more detailed description thereof is not needed herein.

In operation of the fuel injection pump described above, the fuel oil-which is being injected by the plunger barrel 21 into the fuel injection lines 31-1is under great pressure and a portion of the fuel leaks along the surfaces of the plunger barrel 21 and its guide ways within the housing in downward direction. The leaking fuel oil accumulates in injection compartment 151 of the housing 15 and leaks therefrom along the cylindrical surfaces of the associated plunger tappet 28 and its guide way into the cam shaft compartment 12-1. In the past, the fuel oil which thus leaks into the cam shaft compartment 12-1 of such fuel oil injection equipment resulted in the accumulation of leaking fuel at high level in the cam shaft compartment 121 and has been the cause of great diificulties and troubles, as, for example, by interfering with the proper lubrication of the cam surfaces.

The present invention makes it possible to prevent excessive accumulation of leaking oil above an objectionable level within the cam shaft compartment 121 of such injection pump equipment without adding to the moving mechanical elements of the equipment.

In accordance with the invention, the motion transsupply pump tappet 51 and its cylindrical guide space of the supply pump coupling portion 42 are modified for operation as a leakage oil pump which pump excess of oil from the cam shaft compartment 121 and returns it to the fuel oil supply or otherwise discharges it. To this end, the inward end region of the cylindrical guide space 52 of coupling portion 42 is provided with a discharge passage 71 for discharging oil from the guide space 52 into a discharge pipe line 72 when the pump tappet 51 is moved to its inward left position (Fig. 4). In addition, the cylindrical tappet guide space 52 is provided with inlet passages 75 at the region near the inner end of the tappet 51 at its outermost right position (Fig. 4) so that vacuum created in the free tappet guide space 52 will draw oil from the surrounding cam shaft compartment space 12-1 into the tappet guide space 52. The inlet openings 75 into the tappet guide space 52 are positioned so that they are automatically closed by the cylinder surface of the pump tappet 51 in the initial part of its inward movement (Fig. 4) so that further inward movement of the pump tappet 51 causes it to act as a pump piston and eject the oil from the tappet guide space 52 by way of discharge ducts 71 and the associated check valve 73 into a leakage oil return duct or discharge pipe line 72 which is connected to the sump duct outlet 181 through which excess oil is returned by way of oil return line 33.

The inlet openings 75 of the cylindrical tappet guide space 52 of the supply pump tappet 51 are positioned below or at the level of the central region of the cam shaft 12 within the cam shaft compartment 121 of the injection pump housing 15. As a result, the pumping action of supply pump tappet 51 pumps from the cam shaft compartment any oil rising above the level of the oil inlet openings 75 of the pump space of pump tappet 51 and prevents accumulation of leaking fuel oil above the central region of cam shaft 12. Actual operation of the standard fuel oil injection equipment provided with its standard fuel supply pump 40 which was modified in accordance with the invention as described above has established that pumping action of the supply pump tappet 51 removes excess of leakage fuel oil and prevents its accumulation above the central region of the cam shaft 12 and thereby overcomes the difiiculties and troubles caused in the past because of accumulation of leaking fuel oil above the upper level of the cam shaft within the cam shaft compartment.

The features and principles underlying the invention described above in connection with specific exemplifications will suggest to those skilled in the art many other modifications thereof. It is accordingly desired that the appended claims shall not be limited to any specific features or details shown and described in connection with the exemplifications thereof.

I claim:

1. In a fuel oil injection pump for injecting an accurately metered quantity of fuel oil within a predetermined synchronized timing period under high pressure to spray nozzles of cylinders of a diesel engine, which pump comprises a rotatably mounted cam shaft positioned within a housing at the lower portion of said pump and having at least one cam lobe and at least one slidably mounted plunger member actuated by rotation of said lobe for delivery of said metered fuel quantity to one of said cylinders, a supply pump for supplying oil from an oil supply to said plunger member, said supply pump comprising a housing body having a pump space and also a guide space, a pump member slidably movable in said pump space for pumping oil from said oil supply in one stroke and discharging said oil toward said plunger member in the opposite stroke, a tappet member slidably positioned in said guide space for actuation by said cam lobe and operatively linked to said sup ply pump memberfor' translating the rotary motion of said cam lobe into opposite pump strokes imparted to said pumping member, a portion of the oil supplied-to said plunger member tending to leak and accumulate in the cam shaft region of said cam shaft housing, an inlet passage in said supply pump housing body extending between said guide space and the cam shaft housing for causing oil present above a predetermined level in the region of said cam shaft to be drawn through said inlet passage into said guide space by one stroke of said tappet member, a discharge passage in said supply pump housing body extending between said guide space to the exterior thereof for causing the oil drawn into said guide space by said one stroke to be discharged through said discharge space by the opposite stroke of said tappet member.

2. In a fuel oil injection pump for injecting an accurately metered quantity of fuel oil within a predetermined synchronized timing period under high pressure to spray nozzles of cylinders of a diesel engine, which pump comprises a first housing structure, a cam shaft rotatably mounted in said housing structure having at least one cam lobe and at least one plunger member slidably mounted in said housing structure and actuated by rotation of said lobe for delivery of said metered fuel quantity to one of said cylinders, a supply pump for supplyin oil from an oil supply to said plunger member, said supply pump comprising a second housing body having a pump space and also a guide space, a pump member slidably movable in said pump space for pumping oil from said oil supply in one stroke and discharging said oil toward said plunger member in the opposite stroke, a tappet member slidably positioned in said guide space for actuation by said cam lobe and operatively linked to' said supply pump member for translating the rotary motion of said cam lobe into opposite pump strokes imparted to said pumping member, a portion of the oil supplied to said plunger member tending to leak and accumulate in the region of said first housing which surrounds said cam shaft, an inlet passage in said second housing body extending between said guide space and the first housing structure in the region adjacent the said cam shaft for causing oil present above a predetermined level in the region of said cam shaft to be drawn through said inlet passage into said guide space by one stroke of said tappet member, a discharge passage in said second housing body extending between said guide space to the exterior thereof for causing the oil drawn into said guide space by said one stroke to be discharged through said discharge space by the opposite stroke of said tappet member.

3. In a pump as claimed in claim 2, the portion of said second supply pump housing body enclosing said guide space and having said inlet passage being exposed in the interior of said first housing structure in the region of said cam shaft so that said inlet passage defines the maximum level region at which leaking oil will accumulate in the shaft region of said first housing.

References Cited in the file of this patent UNITED STATES PATENTS 2,096,711 Fielden Oct. 26, 1937 

